In the case of such devices, the passage of the plastic strands can be disturbed, e.g., in that a strand contains an inhomogeneity of the plastic, which leads to the strand escaping sideways after issuing from the nozzle and, in so doing, sticking to one or more adjacent strands. Then, it cannot be ruled out that such a bonding of the plastic strands will not result in the sudden conglomeration of the plastic strands, which are then deposited as a chaotic pile on the discharge plate and, in so doing, interrupt the further passage of the plastic strands. Even though such cases rarely occur, there is still the need to signal immediately such trouble, in order to turn off quickly, e.g. the device concerned. To this end, light barriers, which are interrupted by such accumulations of plastic strands and thus trigger the desired signal, have been used directly above the discharge plate. Since at this stage during the operation of such devices vapors are often produced, an interruption was simulated in this manner for such light barriers, so that when such vapors occurred, false alarms were triggered. To eliminate this problem, mechanically acting indicators have been used with which the aforementioned accumulations were detected. These mechanical devices comprise a pivotable flap, which is disposed above the discharge plate and which is arranged in such a manner that during normal service the strands can run off unimpeded below the flap. If, however, an accumulation does form on the discharge plate, during its formation the accumulation displaces the flap out of its normal position, a procedure that is exploited to generate the desired signal. However, it has been demonstrated that the contact between flap and the still molten plastic strands forming the accumulation led to coalescing with the flap, resulting in the flap having to be cleaned after the completed deflection, a procedure that was very difficult to accomplish due to the sensitivity of the flap, since, in so doing, one had to avoid damaging the sensitive bearing of the flap.